Abstract Inter-well heterogeneities influencing fluid migration in deltaic reservoirs are controlled by lateral lithofacies changes and vertical complexities such as low permeability (mudstone) thin-beds. Subsurface tools cannot adequately predict the spatial and stratigraphic organization of these architectural elements, nor their influence on effective reservoir properties and connectivity. Our outcrop-based geomodeling study of the Turonian Wall Creek Member of the Frontier Formation in the Powder River Basin, Wyoming, USA, integrates subsurface production and flow simulation data to quantify the impact of multi-scale stratigraphic heterogeneity on analogous reservoir behavior and horizontal well design. The upscaled representation of thin-bed complexity in our 500 m × 715 m x 15 m geomodel is derived through flow simulation of internally nested, facies specific, centimeter-scale models (basic depositional element models or BDEMs). These BDEMs are populated with quantitative data of mudstone thin-bed geometries directly derived from digital outcrop measurements and measurements in the field, and aided by subsurface (core) petrophysical properties. Reservoir simulations are performed using various landing zone and completion configurations, and under both single-phase and multi-phase flow conditions history matched to subsurface production data. Results from our workflow demonstrate that, in heterolithic settings, the permeability of mudstone thin-beds impart the most significant impacts toward upscaled reservoir behavior, and deliver unique Kv/Kh flow anisotropies dependent on the governing depositional environment. Thin, laterally continuous and planar mudstone beds in the wave-and river-dominated distal delta front setting have the greatest negative effect on Kv and a minimal impact on Kh, promoting laterally continuous and vertically baffled flow units. Conversely, the more curvilinear and intersecting architectures of mudstone beds in the tidal dune facies maintain better vertical connectivity but decreased Kh compared to the wave-influenced facies. Reservoir flow is only sensitive to changes in engineering design (landing zone, well orientation, completion size) where thin-beds act as complete barriers rather than baffles to flow. Layer cake subsurface models failing to account for high-resolution stratigraphic architectures are likely to overestimate reservoir production where thin-beds act as barriers capable of appreciable reservoir compartmentalization, which in our models is more characteristic of the distal delta front setting. Synthesized results of this study are immediately applicable toward development planning in similar tight sandstone reservoirs.

中文翻译：

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美国怀俄明州粉河盆地 Turonian Wall Creek Member of the Frontier Formation 的露头和地下综合地质建模

摘要 影响三角洲储层流体运移的井间非均质性受横向岩相变化和垂向复杂性（如低渗透（泥岩）薄层）的控制。地下工具无法充分预测这些建筑元素的空间和地层组织，也无法预测它们对有效储层特性和连通性的影响。我们对美国怀俄明州粉河盆地 Frontier 组的 Turonian Wall Creek 段进行基于露头的地质建模研究，整合了地下生产和流动模拟数据，以量化多尺度地层非均质性对类似储层行为和水平井的影响设计。在我们的 500 m × 715 mx 15 m 地质模型中，薄层复杂性的放大表示是通过内部嵌套、特定相、厘米级模型（基本沉积元素模型或 BDEM）的流动模拟得出的。这些 BDEM 填充有泥岩薄层几何的定量数据，这些数据直接来自数字露头测量和现场测量，并辅以地下（岩心）岩石物理特性。储层模拟是使用各种着陆区和完井配置进行的，并且在与地下生产数据匹配的单相和多相流条件下进行。我们工作流程的结果表明，在异岩环境中，泥岩薄层的渗透率对放大储层行为产生最显着的影响，并根据控制沉积环境提供独特的 Kv/Kh 流动各向异性。在波浪和河流主导的远三角洲前缘环境中，薄的、横向连续的平面泥岩层对 Kv 的负面影响最大，对 Kh 的影响最小，促进了横向连续和垂直挡板的流动单元。相反，与受波浪影响的相相比，潮汐沙丘相泥岩床的曲线和交叉结构越多，垂直连通性越好，但 Kh 降低。储层流量仅对工程设计的变化（着陆区、井位、完井尺寸）敏感，其中薄层充当完整的屏障而不是流动的挡板。未能考虑高分辨率地层结构的层饼地下模型可能会高估储层产量，其中薄层充当能够进行明显储层划分的屏障，在我们的模型中，这更具有远端三角洲前沿设置的特征。本研究的综合结果可立即应用于类似致密砂岩储层的开发规划。